Over the last two years, I learned enough parts in "The Continuing Story of Bungalow Bill" to make it worth recording. In February 2017, I learned the bass part and the mellotron trombone part at the end, and last September, I learned the organ part. In reading Lewisohn's The Complete Beatles Recording Sessions, I discovered that what I thought were guitar tremolos are actually played with a mandolin sound on mellotron (Chris Thomas, who played both mellotron parts, describes this on page 160). I believe this simply doubles the organ part, albeit an octave lower. I referenced The Beatles Complete Chord Songbook for the chords.
My recording is just a section of the song, roughly 1:23 to 2:30.
I used the mellotron samples available on the Nord website (played on my Electro 5D). There are two trombone sounds available, and I used the Mk I sound. Flipping back and forth between my recording and the original, it sounds exactly the same (although I think I played the part with too much legato; I should have broken up the phrases a little).